This application relates to an auxiliary power unit for an aircraft, wherein a single speed sensor has its sensed signal utilized by two distinct components.
Auxiliary power units are known, and are utilized in aircraft to provide power in addition to the aircraft's main jet turbine engines. Typically, an auxiliary power unit (APU) can include a small turbine engine. An APU is provided with an electronic control box that controls the operation of the APU. A speed sensor will typically send a speed signal from the APU shaft to the electronic control box, where it is utilized for various control functions.
In addition, more and more monitoring systems are being incorporated into the aircraft environment. One such system is an aircraft health monitoring system which may monitor overall health of several aircraft components. The aircraft health monitoring system also needs a speed signal from the APU. The use of redundant sensors would be expensive.